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CFM for BTU
Convert sensible BTU/h cooling load to CFM at a chosen supply-temperature differential. Standard sensible-heat formula: CFM = BTU/h ÷ (1.08 × ΔT).
Supply airflow
1,667 CFM
36,000 BTU/h ÷ (1.08 × 20°F) = 1667 CFM.
Sensible only. Latent (dehumidification) load adds CFM in humid climates — defer to Manual J / N for full design.
How it works
Sensible cooling: BTU/h = 1.08 × CFM × ΔT (where ΔT is the temperature drop across the cooling coil). Rearranged for CFM gives BTU/h ÷ (1.08 × ΔT). The 1.08 constant comes from 60 min/hr × 0.075 lb/ft³ × 0.24 BTU/lb·°F at standard air density.
Typical commercial cooling ΔT = 18-22°F. Tight specs (precision cooling) run 14-16°F. High-temperature distribution runs 22-26°F. Latent (humidity) load requires a separate calculation — this is sensible-only.
Built by Forward
Forward runs CFM-for-BTU, duct sizing, HVAC load, ventilation CFM required, and the broader NEC/IBC/IMC/IPC catalog over text.